Most present side-branch reactive silencers such as resonators and 1/4-wave tuners are either integrated into the air cleaner or attached thereto and take up space in the engine compartment causing packaging, serviceability, access and/or cooling problems.
Approaches heretofore have focused on incorporating the resonator into the air cleaner construction. One such approach is the design disclosed in Kostun U.S. Pat. No. 4,790,864, which discloses a structure incorporating a resonator and a venturi into the air cleaner construction. This air cleaner/sound attenuator assembly is attached to or near the engine, and not below the engine in the waste space area, thereby compounding packaging problems.
Kawamura U.S. Pat. No. 4,136,756 discloses another example of a resonator incorporated into the air cleaner housing. The intake air muffler is intended for use with a motorcycle. The intake air muffler utilizes the muffler case as an air conduit does not rely on existing components of the vehicle to form a resonator.
Lowther U.S. Pat. No. 2,299,157 and Wilson U.S. Pat. No. 2,325,352 both disclose examples of mounting resonators in connection with the air cleaner or the intake manifold constructions. The Lowther device operates as a silencer by restricting and breaking-up sound waves rather than relying on resonant tuning. The Wilson device discloses a resonator having a side-branch design. Specifically, annular channels attach to the resonance chamber to silence noise associated with air intake. However, the Wilson resonators are not part of a subframe nor are they interposed between an engine and a vehicle body.
Thornburgh U.S. Pat. No. 4,778,029 discloses an engine air inlet and silencer directed to vehicles utilizing an engine compartment hood to form a duct to the engine air cleaner assembly. The Thornburgh device is specifically directed to a hood duct inlet and does not address the packaging concerns of the present invention.
Hanzawa et al U.S. Pat. No. 4,800,985 discloses an air intake silencer with a partially flexible side-branch tube. The side-branch tube having a closed end for attenuating high-frequency noise and a resonator chamber for attenuating low-frequency noise. However, this approach mounts to the upper portion radiator resulting in further crowding of the engine compartment. In addition, this device is constructed of many elements, increasing the complexity of the system and the likelihood for failure of the entire system caused by failure of one of the components.
In the foregoing background art no attempts have been made to combine the beneficial features of a large volume, hollow and rigid tubular engine subframe resonator. No use has been made of an existing subframe as a reactive silencer for reducing engine air intake noises and vibrations while providing for compactness and eliminating the space normally required for the resonator.
The present invention to the contrary, is directed to the use of a subframe as a reactive silencer for reducing engine noises and vibrations and also for compactness in eliminating the space normally required for the resonator.